Coal stoker



P. A. LEAS March 26, 1940.

con. s'roxsn Filed June 24, 1939 Patented Mar. 26, 1940 UNITED STATES PATENT OFFICE rm a utfxfiem, m. Applicatizn 215,516

The invention relates generally to coal stokers, and more particularly, to coal stokers utilizing a plunger type of feed mechanism.

The invention has among its objects the pro duction of such a stoker which is simple and durable in construction and eflicient for the purpose intended.

Another object of the invention is the production of a stoker having a substantially non-clogging barrel and plunger.

A further object of the invention is the production of such a stoker in which the driving or feeding portion of the plunger is positioned at the top of the barrel, thereby placing it above the coal dust, dirt, etc., that might accumulate in the barrel and affect efficient operation of the device.

Another object of the invention is the production of such a stoker which is comparatively compact and which may be easily and conveniently moved about.

Many objects and. advantages of the construction herein shown and described will be obvious to those skflled in the art from the disclosure herein given. n

To this end my invention consists in the novel construction, arrangement and combination of parts herein shown and described and more particularly pointed out in the claims.

In the drawing wherein like reference characters indicate like or corresponding parts:

Fig. 1 is a side elevational view of my stoker shown in operating position in a furnace or boiler, with the plunger and barrel shown in section;

5 Fig. 2 is a plan view of the plunger removed from the barrel; and

Fig. 3 is a side elevational view of the same.

Referring to the drawing, and more particularly to Fig. 1, l represents a portion of an 0 ordinary boiler or furnace, having the usual fire box 2, fire opening 3, grates 4 and a draft door 5 communicating with the ash pit. Positioned adjacent the furnace or boiler l is shown a stoker embodying the features of the present I 45 application and comprising a frame 6 supported by suitable legs 1 which are preferably reinforced by braces 8. The device is constructed preferably with three legs, two adjacent the furnace and one at the opposite side of the device so that 50 the latter will always be firmly resting on the vice to be readily moved about, and if desired, the castors may be adjustably mounted on the legs whereby the latter may be adjusted in length to accommodate the device to various types of boilers or furnaces. Carried by the frame 6 and ex- 6 tending through the opening 3 into the furnace I is a stoker barrel Ii which is preferably of a rectangular cross section, and constructed as a casting. Positioned in the barrel II is a plunger l2 also preferably made as a casting, which is also 10 of a general rectangular cross section and is slidable in said barrel. By constructing both the barrel and plunger of rectangular cross section, the plunger is always correctly positioned in the barrel without the use of separate guides, etc., therefor. Likewise, by utilizing a hollow barrel instead of a trough, the fuel in the barrel, at the time the stoker stops in the ordinary course of operation, will not be consumed, thus preventing the depositing of an ash on the fire when the 20 stoker again resumes operation. Also carried on the frame 6 is a motor I 3 and a gear box I, the motor being operatively connected through the gear box l4, crank shaft l5 and connecting rod l6 to the plunger l2 by means of the wrist pin 25 I! carried by the plunger. The barrel II is provided with a rectangular shaped opening l8 adjacent the top thereof and a suitable hopper i9 is provided, positioned alone and communicating with said opening, one side 2 I of the hopper being 50 vertical and the other three sides sloping toward said opening so that the coal or other fuel will feed by gravity into the barrel through the opening i8.

As shown in Fig. 1 and more particularly in Figs. 2 and 3, the plunger I2 is provided with a channel or aperture 22 adapted to register with the opening 48. The rear portion 23 of the plunger which is attached to the connecting rod I1 is substantially hollow and extending from the inner 0 face of the top and bottom thereof are the bosses 24 adapted to receive the wrist pin II, the latter being inserted from the top of the plunger. The front face 25 of the portion 23.which is adjacent the bottom of the barrel II is substantially vertical so that the same will force the fuel along the barrel as the plunger is reciprocated while the wall 26 which forms the rearside wall of said. aperture is inclined rearwardly from the face 25, thus urging the fuel into the lower portion m of the barrel where the face 25 will propel it into the fire box 2. Extending laterally from the portion 23 are walls 21 forming the side walls of the aperture 22 and supporting the forward portion 28 of the plunger which is positioned in 68 the upper portion of the barrel above thefuel feeding into the fire box. By positioning the forward portion of the plunger above the fuel in the barrel, it is above the bed of dust that would ing up of dust under the end of the plunger or other moving parts often causes very severe binding of the parts in the barrel, while in my device this objection is entirely eliminated. The portion 28 is provided with a series of inverted steps 29 which decrease in thickness towards the end 3| of the plunger, the latter being adjacent the mouth 32 of the barrel II. The portion 28 is provided with a central rib 33 which reinforces and strengthens that part of the plunger, thus allowing the plunger to be as light as possible, at the same time providing adequate strength.

The application and operation of the device is as follows:

The usual door is removed from the fire opening 3 and the barrel llinserted therethrough into the fire box of the boiler, the mouth 32 of the barrel being substantially centrally positioned over the grates. The opening 3 is then sealed by means of a suitable plate 34, thereby preventing any draft from entering the fire box other than through the regular draft door 5 and through the grates 4 as in ordinary operation of the furnace without the use of a stoker. I have found it desirable to utilize only the ordinary draft of the furnace through the grates as I have found this to give the most efiicient result, the coal being reduced to a fine powdery ash with no ,clinkers, thus rendering it unnecessary to dump the grates of the furnace more often than once in two or three months. As there are preferably only three legs I supporting the device, it will always be resting firmly on the fioor regardless of unevenness, etc. of the latter. Likewise, if it is desired to disconnect the device in the summer or when not in use, the same may be easily moved about on the castors 8, and if the latter are adjustably mounted, the device may be raised or lowered to position it to any desired height, thus enabling the stoker to be used in combination with furnaces of various sizes and dimensions. The hopper I9 is then'filled with fuel, preferably com paratively fine coal which will feed through the opening [8 in the barrel and the aperture 22 in the plunger into the lower portion of the barrel, and at each stroke of the plunger l2 will be moved along the barrel H and out of the mouth 32 thereof into the fire-box, the vertical face 25 of the plunger imparting the forward motion to the coal in the barrel. Likewise, it will be noted that the inclined surface 26 will tend to raise the coal in the aperture 22 as the plunger moves forward,

thus agitating the coal supply at its narrowest point of travel through the hopper, thereby insuring against possible packing of the fuel at this point and consequent failure to feed down through the metering orifice on the return stroke. The stroke of the plunger should preferably be of such a length to position the upper end of the inclined surface 28 just back of the rear edge of the opening [8 when the plunger is at the end of its forward stroke so that all coal dust etc. will be deflected down into the barrel rather than on the top of the plunger where it might have a tendency to work out of the rear end of the barrel during the rearward half of the plunger stroke. As the coal moves towards the mouth I2 of the barrel, the steps 29 on the plunger decrease in thickness, to provide a continuously expanding space for the coal to occupy as it progresses forward, thereby preventing any wedging or packing of the coal in the barrel as it is being fed into the fire box.

It will be seen from the above description that I have provided a stoker which is simple in operation, which may be easily adjusted to be used in conjunction with various styles of furnaces, and employing a novel construction of the barrel and plunger whereby the same is very efllcient and non-clogging.

Having thus described my invention it is obvimic that various immaterial modifications may hopper communicating with said opening, a

plunger positioned in said barrel, means for reciprocating said plunger therein, that portion of the plunger intermediate said opening and the mouth of the barrel occupying the upper portion of the latter and having a series of inverted horizontal steps, said plunger having an aperture connecting said opening and the lower portion of said barrel, the face of said plunger below said aperture adjacent the lower portion of said barrel being substantially vertical, and that above said face and forming a side wall of said aperture inclined rearwardly from said face, the stroke of said plunger being of a length to position the top edge of said inclined surface rearward from the rear edge of said opening, when the plunger is at the forward end of its stroke.

2. In a stoker of the kind described, a barrel of substantially rectangular cross section and having a rectangular shaped opening adjacent the top thereof and spaced from the barrel mouth, a hopper communicating with said opening, a plunger positioned in said barrel, means for reciprocating said plunger therein, that portion of the plunger intermediate said opening and the mouth of the barrel occupying the upper portion of the latter and having a series of inverted horizontal steps decreasing in thickness toward the mouth of the barrel, said plunger having a rectangular aperture connecting said opening and the lower portion of said barrel, the face of said plunger below said aperture adjacent the lower portion of said barrel being substantially vertical, and that above said face and forming a side wall of said aperture inclined rearwardly from said face, the stroke of said plunger being of a length to position the top edge of said inclined surface at or rearward from the rear edge of said opening. 

